Apparatus for transporting and positioning a capsule in which a radioactive source is present

ABSTRACT

An apparatus is described for transporting and positioning a capsule, in which a radioactive source is present, from a screened safe into an applicator to be temporarily placed in the body of the patient. The apparatus is provided with a safe for storing at least one capsule and with a larger number of applicators, which can be connected, via transport tubes, to passages in a switch-connecting plate, wherein the capsules, or a dummy instead of one of the capsules, can each, via their own tube and switch, independently of one another, be introduced into a transport tube selected by the respective switch and can be displaced therein independently of one another in a manner programmable with regard to location and residence time, by a transport wire slidable via a drive motor.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority of Netherlands Application NL 1026130,filed on May 6, 2004, the contents of which are expressly incorporatedherein by reference in their entirety including the contents andteachings of any references contained therein.

FIELD OF THE INVENTION

The invention generally relates to apparatuses for transporting andpositioning a capsule, in which a radioactive source is present, from ascreened safe into an applicator to be temporarily placed in the body ofthe patient.

BACKGROUND OF THE INVENTION

One such apparatus of the type generally referred to above is describedwithin DE 41.23.501 describing an apparatus including: a capsuleconnected with one end of a transport wire, which is slidable by a drivemotor; a safe for storage of the capsule and provided with a channelfrom taking the capsule into and out of the safe via the transport wire;at least one applicator; a number of transport wires corresponding withthe number of applicators, which each have a first end connected to anapplicator; a switch-connecting plate with multiple passages, whereineach second end of each transport tube is connected to a passage; aswitch with a passageway which, on the one hand, can successively bebrought into a position in line with one of the passages in theswitch-connecting plate and, on the other hand, connects to a first endof a tube whose other end connects to the channel through the safe; andat least one farther switch with a passageway, which can be brought inline with one of the passages in the switch-connecting plate, just likethe passageway of the first switch, so that a further capsule on afurther transport wire can be displaced by a further drive motor throughthe transport tube connecting to the passage selected by the position ofthe further switch.

With such an apparatus, a capsule can be introduced into an applicatorto be selected by setting of the switch and can be stopped at differentlocations to locally effect a concentrated radiation in the body of apatient. Said publication discloses an independently controlled switchto guide a dummy capsule into the applicator for testing purposes. Withincreasing age of the radioactive source, the dose rate released by thecapsule decreases, as a result of which the radiation time needs to beprolonged. If this dose rate is too low, the capsule with theradioactive source present therein needs to be replaced.

SUMMARY OF THE INVENTION

The invention contemplates improving upon an apparatus of the typedescribed in the opening paragraph such that the radiation time canalways remain as short as possible in the course of time and, at thesame time, the capsule can be utilized as optimally as possible.

This is achieved according to the invention by providing the apparatuswith actuators for actuating said switches and said transport wires,said actuators being programmable so that, from the safe, via the tube,the passageway, a passage determined by the position of the switch and atransport tube connected thereto, said capsules can be introduced intoan applicator and can be withdrawn into the safe again, in a mannerindependent of other capsules with regard to location and residencetime. These measures, which can be realized with relatively small extrapurchasing costs, make it possible to select a specific radiation to becarried out for a combined radiation via multiple older and/or youngercapsules, so that, on the one hand, the radiation time can be minimizedand, on the other hand, also, effective use can still be made of oldercapsules, which is advantageous both with a view to costs and to theenvironment.

The apparatus embodying the present invention has additional advantages.By using a further drive motor, the possibility of further variation ofthe radiation pattern is obtained, in that, for instance, isotopes canbe combined, the energy per isotope being different. It is thus possibleto radiate locally with a lower depth dose, so that organs in the humanbody can be spared.

By using the capsules for a longer time giving a higher dose or inlarger volume implants, further, the advantage of a greater versatilityof the apparatus is obtained. Because capsules with relatively lowenergy are available as well, it is further possible to use theapparatus in a slightly screened operating room.

A further advantage of using a further drive motor is that it cansubstantially reduce waiting time for hospital staff. For mosttreatments, use can be made of multiple applicator tubes, for instanceto irradiate a larger volume tumor. Prior to directing a capsule througha transport tube, it can be checked using a dummy whether the paththrough the transport tube and the applicator is clear of obstacles, ascaused by a kinked or bent transport tubes and applicators. If atreatment needs to take place with a multiple number of applicatortubes, then, during the carrying out of a treatment, it can be checkedusing a dummy whether the path through a further transport tube and theapplicator is clear for the next treatment. Thus, the total time of atreatment session can be reduced, so that more treatments can be carriedout per time unit, which improves both productivity and efficiency.

As an applicator, a hollow needle can be used, which is couplable with atransport tube. In order to be able to carry out a treatment asoptimally as possible with as few harmful side effects as possible,multiple needles can be provided around a tumor, such as for instance upto 40 needles. In order to be able to further optimize the radiationpattern in the presence of at least one further drive motor, so thatdifferent applicators can simultaneously be placed in mutually differentcapsules, it is preferred according to a further embodiment of theinvention that the drive motors are servomotors or stepping motors,which are able to place the capsules in, for instance, 1 to 400different positions, so that, particularly with combined radiation, alarge variety of radiation patterns are possible in that location,residence time and displacement of the capsules relative to one anotherare changeable. When the apparatus is not in use or when an applicatoris placed, the radioactive source capsules are stored in a screenedsafe. For placing an applicator and determining a radiation schedule,use can be made of the dummy, which is also used for testing whether thepath for a capsule is clear. As is well-known, such a dummy can be keptoutside the storage holder if desired. By displacing the dummy inaddition to two or more capsules with their own drive motors, a furtheroptimization with regard to combined radiation and reducing the totaltreatment time can be obtained.

Taking, as desired, two or more capsules and optionally also a dummy todifferent transport tubes to be selected from a series of transporttubes is made possible by using a number of switches. In order to beable to operate in an optimal manner, it is preferred according to afurther embodiment of the invention that each switch is provided with aconnecting element, the connecting elements of the respective switchesbeing displaceable independently of one another. Thus, a maximum freedomis obtained with regard to radiation, positioning and testingoperations. An option to be considered here are connecting elementswhose passageways are sendingly displaceable on, for instance, multiplelevels on the switch-connecting plate. According to a further embodimentof the invention, however, it is preferred that the connecting elementsare mutually independent pivoting arms, which are provided with apassageway and are pivotable about a common centerline, around whichcommon centerline the passages are arranged so as to be radiallysymmetrical with their centerlines and parallel to that commoncenterline. By a simple pivotal movement, the desired transport tube canthen be approached. In order to save costs, it is preferred that theindividually drivable pivoting arms are alternately drivable by the samemotor, which can be realized by means of a simple sliding coupling andis partly made possible by the fact that simultaneously approaching twotransport tubes is no requirement.

In order to guarantee an exact connection between a passageway and atube, according to a further embodiment of the invention, it can beprovided that the pivoting arms are controlledly displaceable in thedirection of the common centerline, which can be carried out quickly andcontrolledly in an effective manner if a pulling magnet is present forbeing able to displace them in a controlled manner, which magnet candisplace each of the pivoting arms, which are forced in the direction ofthe common centerline towards the switch-connecting plate, individuallyin opposite direction.

In view of the nature of the objects to be transported, capsules inwhich a radioactive source is present, it is important to know when acapsule has left the safe and when it has returned therein again. Forthis purpose, it is further proposed according to the invention that, inor near a passageway or passage, a detector, preferably mounted on aconnecting element, is provided for recording whether or not a capsule,a dummy or a radioactive source passes. Further, this detector can bedeployed for checking whether the capsule sees the source pass at theright moment on its way to the applicator. Further, the detector servesto check whether the transport tube has been connected correctly andwhether the right channel has been connected through.

In another aspect, the invention relates to a method of operating anapparatus according to any one of the preceding claims, wherein saidmethod comprises: determining for each location a desired radiation doseto be received; selecting for each of said locations a number ofcapsules each having a predetermined dose rate; determining a radiationschedule for each of said number of capsules; and calculating for eachof said number of capsules a corresponding residence time in each ofsaid locations.

BRIEF DESCRIPTION OF THE DRAWINGS

The appended claims set forth the features of the present invention withparticularity. The invention, together with its objects and advantages,may be best understood from the following detailed description taken inconjunction with the accompanying drawings of which:

FIG. 1 shows, in perspective, an apparatus according to the invention;

FIG. 2 shows a side elevational view of the apparatus according to FIG.1; and

FIG. 3 shows a first and second table example comprising a schematicnumerical example of combining multiple capsules in order to reducetreatment time.

DETAILED DESCRIPTION OF THE DRAWINGS

The Figures diagrammatically show three drive units 1, 2 and 3, whichare each, in the conventional known manner, provided with inter alia, adrive motor, which is preferably designed as stepping motor and canoperate a storage for a transport wire, and a safe 4 for the storage ofcapsules, in which a radioactive source can be present, and a switchshown in more detail and generally designated by reference numeral 5.

The switch 5 is provided with a motor 6, which is fixedly arranged in aframe of the apparatus not shown in more detail, just like a supportingarm 7, which bears, via two pins 8, a switch-connecting plate 9 formedby a plate assembly, in which a large number of passageways 10 have beenprovided in a radially symmetrical manner. On a side facing away fromthe motor 6, a passageway of the passageways 10 terminates in aconnecting piece 11 to which, as known per se, a transport tube (notshown) can be connected, which leads to an applicator (not shown either)to be temporarily placed in the body of a patient. Such an applicatormay be a hollow needle, which is positioned with respect to a tumor tobe radiated. From the side facing away from the connecting piece 11,each passageway 10 is accessible to a coupling element 12, which isslidably received in a guide part 13, each coupling element 12 beingspring-loaded with respect to the guide part 13 in such a manner thatone end of the coupling element 12 is forced in the direction of thepassageways 10. The other end of the coupling element 12 is connected toa tube 16, which is, in turn, connected to an outlet of the safe 4. Eachguide part 13 is attached to a pivoting arm 14, which is freelyrotatably mounted on shaft 15 of the motor 6.

Normally, a coupling element 12 projects into one of the passageways 10and thereby connects an outlet of the safe 4 with an applicator via thetube 16, a passageway 10 and a transport tube connecting thereto. Acapsule with radioactive source which is present in the safe 4 isconnected with the end of a transport wire of one of the drive units1-3. Using the drive motor of the respective drive unit, the transportwire can be slid such that the capsule is forced out of the safe 4 andis then, via the tube 16, the coupling element 12, the passageway 10 andthe transport tube, introduced into the applicator, where the radiationcan be carried out in a desired manner for predetermined residence timesand from predetermined positions.

It is often preferred to radiate a tumor from different sides and withdifferent intensities. This is possible with the present apparatus inthat multiple coupling elements 12 are provided, which can each, withtheir own pivoting arm 14, be brought in line with a particularpassageway 10 leading to a specific applicator. Testing whether the paththrough a transport tube to an applicator is clear of obstructions, suchas bends in the tube, can be carried out using a dummy, which can bedirected to the applicator via a transport wire by means of a drive unit1-3 in the same manner as a capsule. Both carrying out multipleradiations and checking whether the path to the applicator is clear aresimultaneously possible in the present apparatus by designing the switchsuch that, independently of one another, the various coupling elements12 can be pulled out of a passageway 10 and be brought in line with adifferent passageway 10.

This mutually independent operation is provided by a pulling magnet 17,which can make a rod 18 pivot about its upper hinge point. The rod 18 isfurther provided with a lower free end, which engages in acircumferential groove provided in a wheel 19 fixedly attached to theshaft 15 of the motor 6, which wheel is in turn connected with a controlplate 20 in the form of a round disc with a radius slightly smaller thanthe distance to the coupling elements 12 arranged in a radiallysymmetrical manner. Further, at one location along its circumference,the control plate 20 is provided with a radially projecting cam notshown in the Figures, while each coupling element 12 is provided with acircumferential groove 21, such that the cam can be situated in thecircumferential groove 21 by rotation of the control plate 20 with theaid of the motor 6. By energizing the pulling magnet 17 in thissituation, the control plate 20 is pulled in the direction of the motor6 and thereby takes the respective coupling element 12 along throughcooperation of the cam and the circumferential groove, so that thiselement is pulled out of the passageway 10. By then rotating the controlplate 20 via the motor 6, the withdrawn coupling element 12 can bebrought in line with a different passageway 10, while taking along thefreely rotatable pivoting arm 14. Upon withdrawing the control plate 10,the other coupling elements 12 are not affected and the connections withthe respective applicators realized thereby are maintained.

Thus, with a minimal loss of time, a number of radiations can be carriedout, for instance in that the path to a next location of radiation canalready be checked using a dummy while radiation still takes place at aprevious location. In this manner, the treatment time can be reduced,which is not only more agreeable to the patient, but also increases theeffective operating time of the apparatus and thus reduces the costs.

A very important advantage of the invention is that, by being able touse multiple sources simultaneously, the radiation time can be reduced,while, at the same time, radiation sources can also remain in uselonger, for instance by combining an older and a younger source, whichis advantageous both with a view to the environment and to costs. Inaddition, this makes it possible to radiate locally with a lower depthdose, so that organs in the human body are spared and, when usingcapsules with relatively low energy, the apparatus can also be deployedin a slightly screened operating room.

In the exemplary embodiment shown and discussed, use is made of a switchwith a round, rotatable switch-connecting plate. Of course, differentembodiments are possible as well. An option to be considered arepassageways arranged next to one another in a linear manner, where thecoupling elements are taken upwards or downwards for displacing them andare then slid up to the next passage to be used and are there takenupwards or downwards again.

Because the apparatus uses capsules in which a radioactive source ispresent, it is important to know when a capsule has left the safe 4 andwhen it has returned therein again. This can be realized by providing adetector, preferably mounted at the location of the guide part 13, whichdetector can record whether or not a capsule, a dummy or a radioactivesource passes. Further, this detector can be deployed for partlydetermining the location where the capsule is present in the applicator,and whether the right channel is used and is connected in the rightmanner.

In an exemplary number embodiment, it is assumed that six locations eachneed a radiation treatment of 60 (a.u.). A new source is available of10, an older of 5. In one embodiment, the older source is operatedparallel at the same time the new source is active. Hence, a reductionof radiation time can be realized by 33%. In another embodiment, sixdifferent locations each need different treatment times, and havingthree locations of 20 and three locations of 15. According to theinvention the embodiments of FIGS. 1 and 2 are equipped with a processorthat optimizes a schedule according to a minimal treatment time,treating the locations of 15 in subsequent treatments by sources 10 and5, and treating the locations of 20 by a combination of sources 10 and 5in order to keep the treatment time minimal. Again, a reduction of 33%in treatment time is possible. This example is graphically illustratedin FIG. 3.

It goes without saying that, within the framework of the invention, manyfurther modifications and variants are possible in addition to the onesalready mentioned hereinabove. Options to be considered are two, four ormore coupling elements with associated means. Also, the mechanism fordecoupling, and displacing the coupling elements can be realized in manydifferent manners, where an option to be considered is, for instance,being able to withdraw and pivot the pivoting arms individually.Further, in the exemplary embodiment, the three tubes all connect to theoutlet of the safe. If one of the tubes is used for directing a dummy,this can also be laid around the safe,

1. An apparatus for transporting and positioning a capsule, in which aradioactive source is present, from a screened safe into an applicatorto be temporarily placed in the body of the patient, which apparatus isprovided with: a capsule connected with one end of a transport wire,which is slidable by a drive motor; a safe for storage of the capsuleand provided with a channel for taking the capsule into and out of thesafe via the transport wire; at least one applicator; a number oftransport tubes corresponding with a number of applicators, which eachhave a first end connected to an applicator; a switch-connecting platewith multiple passages, wherein each second end of each transport tubeis connected to a passage; a switch with a passageway which, on the onehand, can successively be brought into a position in line with one ofthe passages in the switch-connecting plate and, on the other hand,connects to a first end of a tube whose other end connects to thechannel through the safe; at least one further switch with a passageway,which can be brought in line with one of the passages in theswitch-connecting plate, in the same manner as like the passageway ofthe first switch, so that a further capsule on a further transport wirecan be displaced by a drive motor through the transport tube connectingto the passage selected by the position of the further switch, whereineach switch is provided with a connecting element, wherein theconnecting elements of the respective switches are displaceableindependently of one another, the connecting elements are mutuallyindependent pivoting arms, which are provided with a passageway and arepivotable about a common centerline, around which common centerline thepassages are arranged so as to be radially symmetrical with theircenterlines and parallel to that common centerline, wherein the mutuallyindependent pivoting arms are alternately drivable and the pivoting armsare controlledly displaceable in the direction of the common centerline;actuators for actuating said switches and said transport wires, saidactuators being programmable so that, from the safe, via the tube, thepassageway, a passage determined by the position of the switch and atransport tube connected thereto, said capsules can be introduced intoan applicator and can be withdrawn into the safe again, in a mannerindependent of other capsules with regard to location and residencetime; and said apparatus characterized in that, for enabling controlleddisplacement, a pulling magnet is present, which can displace each ofthe pivoting arms, which are forced in the direction of the commoncenterline towards the switch-connecting plate, individually in oppositedirection.
 2. The apparatus of claim 1, wherein during the displacementof one of the switches, each further switch remains blocked.
 3. Theapparatus of claim 1 wherein, in or near a passageway or passage, adetector is arranged for recording whether or not a dummy or aradioactive source passes.
 4. The apparatus of claim 3 wherein thedetector is mounted on a connecting element.
 5. The apparatus of claim 1wherein the drive motors are stepping motors.
 6. The apparatus of claim1 wherein the safe has multiple channels.
 7. The apparatus of the typerecited in claim 1 further comprising a processor programmed to controlsaid actuators, said processor carrying out the steps of: determiningfor each location a desired radiation dose to be received; and selectingfor each of said locations a number of capsules each having apredetermined dose rate; determining a radiation schedule for each ofsaid number of capsules; and calculating, for each of said number ofcapsules, a corresponding residence time in each of said locations.
 8. Amethod of operating the apparatus defined in claim 1, wherein saidmethod comprises: determining for each location a desired radiation doseto be received; and selecting for each of said locations a number ofcapsules each having a predetermined dose rate; determining a radiationschedule for each of said number of capsules; and calculating, for eachof said number of capsules, a corresponding residence time in each ofsaid locations.
 9. The method of claim 8, wherein said radiationschedule is determined to minimize a treatment time.
 10. A methodaccording to claim 8, wherein said radiation dose delivered originatesfrom different pre-selected isotopes.